1. Field of the Invention
The present invention relates to an IrDA communication IC for adding a communication function complying with the IrDA (Infrared Data Association) standards to an electronic apparatus, such as a DSC (digital still camera), personal computer, portable data terminal (also called a PDA (personal digital assistant)), or printer, that is provided with a data transfer port. The present invention relates also to an electronic apparatus having such an IrDA communication IC, and also to an externally-fitted communication apparatus having such an IrDA communication IC and designed to be fitted externally to such an electronic apparatus.
2. Description of the Prior Art
In recent years, infrared communication complying with the IrDA standards has come to be used widely as a means for communication between a terminal apparatus such as a personal computer and an apparatus externally connected thereto, achieving wireless communication between the terminal apparatus and the external apparatus. For example, Japanese Laid-Open Patent Application No. H9-326800 proposes a device for achieving such infrared communication complying with the IrDA standards and a method for controlling such a device.
A block diagram of the internal configuration of the infrared communication device proposed in Japanese Laid-Open Patent Application No. H9-326800 mentioned above is shown in FIG. 9. The infrared communication device shown in FIG. 9 has a CPU (central processing unit) 101 for controlling the entire device, a ROM (read-only memory) 102 for storing a program executed by the CPU 101, a RAM (random-access memory) 103 for storing data used by the CPU 101, an external storage device 104 for storing a file and others used by the CPU 101, an operation section 105 through which the device is operated, a display section 106, a UART 107 for exchanging parallel data with a bus 112, a modulation section 108 for modulating a signal output from the UART 107, a demodulation section 109 for demodulating a signal received through an infrared receiver section 111 and then feeding the demodulated signal to the UART 107, an infrared transmitter section 110 for transmitting infrared rays in accordance with a signal output from the modulation section 108, an infrared receiver section 111 mentioned above, and a bus 112 mentioned above for connecting the constituent blocks 101 to 107 together.
To add an IrDA communication function to an already-existing terminal apparatus that does not incorporate IrDA communication capability, the internal configuration of the terminal apparatus needs to be modified to constitute an infrared communication device as described above. To achieve this, an extra software program needs to be added that achieves IrDA communication. Such a software program has a considerably large scale, and therefore, in cases where an already-existing terminal apparatus is modified to constitute an infrared communication device, its CPU 101 needs to be run faster to execute the software program, and larger storage capacities are required in its ROM 102 and RAM 103. Thus, it is inevitable to increase the performance of the CPU of the already-existing terminal apparatus and also increase the capacities of the ROM and RAM thereof.
Quite inconveniently, this infrared communication device, having a faster-operating CPU 101 and larger-capacity ROM 102 and RAM 103, consumes an accordingly larger amount of electric power.
An object of the present invention is to provide an IrDA communication IC that has a communication function complying with the IrDA standards and that, in a case where an IrDA communication function is added to an already-existing terminal apparatus, enables the terminal apparatus to perform IrDA communication by being connected to the terminal apparatus with almost no modification in the internal configuration of the terminal apparatus.
To achieve this object, according to the present invention, an IrDA communication IC is provided with: an input/output interface for converting data fed in from outside the IrDA communication IC into parallel data to be processed within the IrDA communication IC, and for converting parallel data output from within the IrDA communication IC into data to be fed out to outside the IrDA communication IC; a protocol control circuit for converting the parallel data fed from the input/output interface into an IrDA-protocol-conforming signal, and for converting an IrDA-protocol-conforming signal fed in from outside and demodulated into parallel data and then feeding this parallel data to the input/output interface; a modulation circuit for modulating the IrDA-protocol-conforming signal fed from the protocol control circuit; and a demodulation circuit for demodulating the signal fed in from outside and then feeding this demodulated signal to the protocol control circuit.
In this IrDA communication IC, the input/output interface may be a serial input/output interface that converts serial data fed in from outside the IrDA communication IC into parallel data and that converts parallel data output from within the IrDA communication IC into serial data.
The above IrDA communication IC may be further provided with a first FIFO circuit connected between the protocol control circuit and the modulation circuit and a second FIFO circuit connected between the protocol control circuit and the demodulation circuit. The first FIFO circuit accumulates IrDA-protocol-conforming data fed from the protocol control circuit, and then feeds this accumulated data to the modulation circuit sequentially on a first-in-first-out basis. The second FIFO circuit accumulates demodulated IrDA-protocol-conforming data fed from the demodulation circuit, and then feeds this accumulated data to the protocol control circuit sequentially on a first-in-first-out basis.
The first FIFO circuit may, when the amount of the data accumulated therein becomes smaller than a predetermined amount, send an interrupt request to the protocol control circuit to notify the protocol control circuit that further data can be accumulated as that data. This helps limit the amount and thereby prevent an overflow of the data accumulated in the first FIFO circuit. On the other hand, the second FIFO circuit may, when the amount of the data accumulated therein becomes larger than a predetermined amount, send an interrupt request to the protocol control circuit to instruct the protocol control circuit to start processing that data on a first-in-first-out basis. This helps limit the amount and thereby prevent an overflow of the data accumulated in the second FIFO circuit.
Another object of the present invention is to provide an electronic apparatus to which an IrDA-complying communication function is added by incorporating a control device having an IrDA-complying communication function into an already-existing electronic apparatus without significant modifications in the hardware software thereof.
To achieve this object, according to the present invention, an electronic apparatus is provided with: an overall controller for controlling the system operation of the electronic apparatus proper; a connector to which a cable is connected to allow communication with an external electronic apparatus and thereby allow exchange of data; a level conversion driver connected between the overall controller and the connector so as to convert the voltage level of the data; an IrDA communication IC connected to the data transfer path between the level conversion driver and the overall controller so as to perform modulation and demodulation and perform conversion of IrDA-protocol-conforming data to allow IrDA-complying communication; and an IrDA transceiver connected to the IrDA communication IC so as to exchange infrared signals with an external electronic apparatus having an IrDA-complying communication function.
In this electronic apparatus, the IrDA communication IC may be provided with: an input/output interface for converting data fed in from outside the IrDA communication IC into parallel data to be processed within the IrDA communication IC, and for converting parallel data output from within the IrDA communication IC into data to be fed out to outside the IrDA communication IC; a protocol control circuit for converting the parallel data fed from the input/output interface into an IrDA-protocol-conforming signal, and for converting an IrDA-protocol-conforming signal fed in from outside and demodulated into parallel data and then feeding this parallel data to the input/output interface; a modulation circuit for modulating the IrDA-protocol-conforming signal fed from the protocol control circuit; and a demodulation circuit for demodulating the signal fed in from outside and then feeding this demodulated signal to the protocol control circuit. Here, the protocol control circuit also controls the operation of the modulation circuit and the demodulation circuit.
Still another object of the present invention is to provide an externally-fitted communication apparatus that allows an IrDA-complying communication function to be added to an already-existing electronic apparatus by being connected thereto.
To achieve this object, according to the present invention, an externally-fitted communication apparatus that is externally fitted to an electronic apparatus to add an IrDA-complying communication function thereto is provided with: an IrDA communication IC for performing modulation and demodulation and performing conversion of IrDA-protocol-conforming data to allow IrDA-complying communication; an IrDA transceiver connected to the IrDA communication IC so as to exchange infrared signals with an external electronic apparatus having an IrDA-complying communication function; and an IrDA communication connector connected to the IrDA communication IC so as to allow exchange of data with the electronic apparatus.
In this externally-fitted communication apparatus, the IrDA communication IC may be provided with: an input/output interface for converting data fed in from outside the IrDA communication IC into parallel data to be processed within the IrDA communication IC, and for converting parallel data output from within the IrDA communication IC into data to be fed out to outside the IrDA communication IC; a protocol control circuit for converting the parallel data fed from the input/output interface into an IrDA-protocol-conforming signal, and for converting an IrDA-protocol-conforming signal fed in from outside and demodulated into parallel data and then feeding this parallel data to the input/output interface; a modulation circuit for modulating the IrDA-protocol-conforming signal fed from the protocol control circuit; and a demodulation circuit for demodulating the signal fed in from outside and then feeding this demodulated signal to the protocol control circuit. Here, the protocol control circuit also controls the operation of the modulation circuit and the demodulation circuit.
By the use of an externally-fitted communication apparatus as described above, addition of an IrDA-complying communication function to an electronic apparatus that has a controller for controlling the electronic apparatus proper, a first connector for allowing exchange of data with an external electronic apparatus, and a level conversion driver connected between the controller and the first connector so as to convert the voltage level of the data and that performs communication with the external electronic apparatus by way of a cable is achieved by providing a second connector connected to the data transfer path between the controller and the first connector and then connecting the IrDA communication connector of the externally-fitted communication apparatus to the second connector.